debugability: logger: add note on DMA trace limitations

kv2019i · kv2019i · commit c3f20782094c · 2021-11-10T12:00:36.000+02:00
If sof-logger is started (or restarted) while DSP is running, the initial traces may come in incorrect order or are incomplete. This is important to note when parsing the logger results. BugLink: thesofproject/sof-test#297 Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
diff --git a/developer_guides/debugability/logger/index.rst b/developer_guides/debugability/logger/index.rst
@@ -136,6 +136,11 @@ Examples
     distribution kernels ``sof_debug=1`` module option for ``snd_sof`` might be
     needed if the /sys/kernel/debug/sof/trace file is not present)
 
+.. note::
+  The DMA trace sysfs interface is a streaming interface. If sof-logger is
+  started (or restarted) while DSP is active, it is possible the initial traces
+  messages are in wrong order or incomplete.
+
 Trace filtering
 ***************
 
